Magnetic rotary contact



y 1959 LA RUE v. REQGELMAN 2,897,468

MAGNETIC ROTARY CONTACT Filed Oct. 5, 1956 INVENTOR LORUE V. REGELMAN ATTORNEY MAGNETIC ROTARY CONTACT La Rue V. Regelman, Emporium, Pa., assignor to Sylvania Electric Products Inc., a corporation of Massachusetts Application October '5, 1956, Serial No. 614,241

3 Claims. (Cl. 339-8) This invention relates to electrical connectors and associated parts. In particular it relates to an electrical connection between a fixed conductor and a second conductor where one of them rotates on a fixed axis with respect to the other but spaced from said other conductor.

It is an object of the invention to provide a connection between the conductors which shall afford good constant conduction of electric current through the connection.

It is a further object of the invention to make a connection between the elements, which, despite the relative rotation of parts, shall have a long life.

It is a still further object of the invention to provide a form of connection between rotating parts which shall be particulate and yet held against the conductors in such a manner as to avoid scattering of the particulate material and which material shall not be of a poisonous nature, as is mercury.

These and other objects of the invention will become apparent on consideration of the following description taken in conjunction with the accompanying drawing in which:

Fig. 1 is a plan view of a simple form of mechanism illustrating an application of the invention, and

Fig. 2 is a vertical elevation, partly in section, of the device of Fig. 1.

Figs. 3 and 4 disclose modifications of a bar magnet retaining arm forming part of the connection of the invention.

Referring to the drawing in greater detail, the invention is illustrated as comprising a rotatable member 18), here shown as a disc type sprocket, cooperating with a stationary member 12 mounted on a stationary support 14, as by bolts 16. In practice the rotating member may be other than a sprocket wheel such as a tool turret so long as it provides means for supporting one of the relatively rotatable conductors. In this instance, the drive shaft 18 of the sprocket is illustrated as conventionally grounded. Supported by the sprocket is a block 20 fastened to the sprocket by bolts 22 and surmounting the block 20, cantilever fashion, is an arm 24 secured to the block by bolts 26. The arm 24 extends over the axis of shaft 18 and coaxially with the shaft is provided with a recess or cup 26. Embedded in the arm 24 is a magnet 28 here shown as a bar magnet. The magnet is, for the sake of maintaining parts slender, laid parallel with the arm 24 though with a wider arm as illustrated in Fig. 3, a pair of such bar magnets 30 and 32 could have been arranged one on each side of the cup and, with a thicker arm, as illustrated in Fig. 4, a magnet 34 could be arranged axially of the cup 26 and embedded in a counterbore within the cup. All of the parts thus far described are preferably made of conductive material. Although the shaft 18 is here shown as conventionally grounded, in actual application of the mechanism other additional grounds are provided as, for example, by the conveyor chain engaging the sprocket 10.

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The arm structure described above constitutes a conductor with the cup rotatable coaxially of the shaft 18. Positioned within the cup but spaced from the walls and bottom thereof is a second magnet 36 in close magnetic relationship to a pole of a bar magnet in the arm 24 and with adjacent poles of the two magnets of opposite polarity. The bar magnet is soldered to the head of a stud bolt 38 preferably by silver solder, as indicated at 40, and preferably the magnet is remagnetized after attachment to the bolt. The bolt is mounted in arm 12 and insulated therefrom by insulating eyelet 42 and washer 44. The stud bolt is secured to the arm by conventional nuts, as nuts 46, between which is secured the ends of a flexible conductor 48 leading to a desired part of the machine. To complete the electrical connection between the lead 48 and the parts supporting the magnet 28, or the magnets of Figs. 3 and 4, the cup is partially filled with a para-magnetic particulate material 50, as for example, powdered nickel. Then under the influences of the magnetic forces existing in the cup, the material will become compacted and crowd about the opposed poles of the magnets and become a material having low electrical resistance and not subject to spill. Also, the paramagnetic materialsiron, nickel and cobalt-are non-toxic and therefore desirable for use as a connector medium over substances such as mercury. Further, with use, the nickel or equivalent material becomes a better conductor, since the relative rotation of parts exercises a grinding function on the powdered ma terial tending to make it more and more pulverulent and by magnetic attraction making the mass of material more and more dense and less and less resistant to the flow of electric current therethrough. To avoid solid contaminants falling into the cup, the underside of the arm may be equipped with a hollow cylindrical shield or skirt 52 of any non-magnetic material arranged concentrically of the cup and extending down close to the upper surface of the arm 24.

Having thus described the invention, what is claimed as new is:

1. An electrical connection between two spaced apart conductors rotative with respect to each other about an axis of rotation, one of said conductors being provided with a cup concentric with the axis of rotation and with a first permanent magnet having a pole exposed to contents of the cap, the second of said conductors termimating in a second permanent magnet having a pole projecting into the cup with the projecting pole of opposite polarity to the said pole of the first magnet and a particulate magnetic material in the cup sufficient to bridge the space between the named poles of the two magnets and form the sole electrically conductive path therebetween.

2. An electrical connection between a rotatable member and a fixed member arranged coaxially of and spaced from the rotatable member, said connection comprising a recess in the rotatable member at the axis of rotation, a permanent bar magnet fixed to the rotatable member and having a pole face flush in the Wall of the recess, a magnetic powder in the recess, a permanent fixed magnet extending coaxially of the fixed member and extending into the recess with the pole of the fixed member of opposite polarity to the said pole of the first magnet, the magnetic material being sufficient to bridge the space between the two poles, said fixed magnet being electrically insulated from the rotatable member, and means for conducting current to the coaxial magnet and to the magnet fixed to the rotatable member, the current through the magnets and the powder forming the sole path for the flow of current between the magnets.

3. An electrical connection between a rotatable memv 3 her and a fixed member arranged coaxially of and spaced from the rotatable member, said connection comprising a. recess in the rotatable member at the axis of rotation, a permanent bar magnet fixed to the rotatable member and having a pole in the wall of the recess, a magnetic powder in the recess, a permanent fixed magnet having a pole extending into the recess with the pole of the fixed magnet of opposite polarity to the said pole of the first magnet, the magnetic material being sufiicient to bridge the space between the two poles, said fixed magnet being mounted in an arm, means electrically insulating said fixed magnet from the arm and means for conducting electric current to the fixed magnet and to the magnet fixed to the rotatable member, the magnetic powder forming the sole electrically conductive path between the magnets.

References Cited in the file of this patent UNITED STATES PATENTS 811,654 Murphy Feb. 6, 1906 2,068,043 Warnke Ian. 19, 1937 2,500,953 Libman Mar. 21, 1950 2,557,140 Razdowitz June 19, 1951 2,650,684 English Sept. 1, 1953 FOREIGN PATENTS 128,831 Australia Sept. 2, 1948 

